NASA 124378main mro-launch-Aug051

8/14/2019 NASA 124378main mro-launch-Aug051

1/47

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

Mars ReconnaissanceOrbiter Launch

Press KitAugust 2005


2/47


3/47

Media Contacts

Dolores Beasley Policy/Program Management 202/358-1753Headquarters [email protected]

Washington, D.C.

Guy Webster Mars Reconnaissance Orbiter Mission 818/354-5011Jet Propulsion Laboratory, [email protected], Calif.

George Diller Launch 321/867-2468Kennedy Space Center, Fla. [email protected]

Joan Underwood Spacecraft & Launch Vehicle 303/971-7398Lockheed Martin Space Systems [email protected], Colo.

ContentsGeneral Release ................................................................................. 3Media Services Information ............................................... 5Quick Facts ................................. 6Mars at a Glance ................................... 7Where We've Been and Where We're Going ................................... 8Science Investigations ............................................................................................................... 12

Technology Objectives .............................................................................................................. 21Mission Overview ................................... 22Spacecraft ................................................................................................................................. 33Mars: The Water Trail ............... 38Historical Mars Missions .................................... 44Program/Project Management .................................. 45

1


4/47

2


5/47

GENERAL RELEASE:

NASA'S NEW MARS ORBITER WILL SHARPEN VISION OF EXPLORATION

NASA's next mission to Mars will examine the red planet in unprecedented detail fromlow orbit and provide more data about the intriguing planet than all previous missionscombined. The Mars Reconnaissance Orbiter and its launch vehicle are nearing finalstages of preparation at NASA's Kennedy Space Center, Fla., for a launch opportunitythat begins Aug. 10.

The spacecraft will examine Martian features ranging from the top of the atmosphereto underground layering. Researchers will use it to study the history and distribution ofMartian water. It will also support future Mars missions by characterizing landing sitesand providing a high-data-rate communications relay.

"Mars Reconnaissance Orbiter is the next step in our ambitious exploration of Mars,"said Douglas McCuistion, director of the Mars Exploration Program in NASAs ScienceMission Directorate. "We expect to use this spacecraft's eyes in the sky in comingyears as our primary tools to identify and evaluate the best places for future missionsto land."

The spacecraft carries six instruments for probing the atmosphere, surface and subsur-face to characterize the planet and how it changed over time. One of the science pay-load's three cameras will be the largest-diameter telescopic camera ever sent to anoth-er planet. It will reveal rocks and layers as small as the width of an office desk. Another

camera will expand the present area of high-resolution coverage by a factor of 10. Athird will provide global maps of Martian weather.

The other three instruments are a spectrometer for identifying water-related minerals inpatches as small as a baseball infield; a ground-penetrating radar, supplied by theItalian Space Agency, to peer beneath the surface for layers or rock, ice and, if pre-sent, water; and a radiometer to monitor atmospheric dust, water vapor and tempera-ture.

Two additional scientific investigations will analyze the motion of the spacecraft in orbitto study the structure of the upper atmosphere and the Martian gravity field.

"We will keep pursuing a follow-the-water strategy with Mars Reconnaissance Orbiter,"said Dr. Michael Meyer, Mars exploration chief scientist at NASA Headquarters."Dramatic discoveries by Mars Global Surveyor, Mars Odyssey and the MarsExploration Rovers about recent gullies, near-surface permafrost and ancient surfacewater have given us a new Mars in the past few years. Learning more about what hashappened to the water will focus searches for possible Martian life, past or present."Dr. Richard Zurek of NASA's Jet Propulsion Laboratory, Pasadena, Calif., project sci-

3


6/47

entist for the orbiter, said, "Higher resolution is a major driver for this mission. Everytime we look with increased resolution, Mars has said, 'Here's something you didn'texpect. You don't understand me yet.' We're sure to find surprises."

The orbiter will reach Mars in March 2006. It will gradually adjust the shape of its orbit

by aerobraking, a technique that uses the friction of careful dips into the planet's upperatmosphere. For the mission's 25-month primary science phase, beginning inNovember 2006, the planned orbit averages about 190 miles above the surface, morethan 20 percent lower than the average for any of the three current Mars orbiters. Thelower orbit adds to the ability to see Mars as it has never been seen before.

To get information from its instruments to Earth, the orbiter carries the biggest antennaever sent to Mars and a transmitter powered by large solar panels. "It can send 10times as much data per minute as any previous Mars spacecraft," said JPL's JamesGraf, project manager. "This increased return multiplies the value of the instruments bypermitting increased coverage of the surface at higher resolution than ever before. The

same telecommunications gear will be used to relay critical science data to Earth fromlanders."

To loft so big a spacecraft, weighing more than two tons fully fueled, NASA will use apowerful Atlas V launch vehicle for the first time on an interplanetary mission.

The mission is managed by JPL, a division of the California Institute of Technology,Pasadena, for the NASA Science Mission Directorate. Lockheed Martin SpaceSystems, Denver, is the prime contractor for the project and built the spacecraft.

For information about Mars Reconnaissance Orbiter on the Web, visithttp://www.nasa.gov/mro

- End of General Release -

4


7/47

Media Services Information

NASA Television Transmission

NASA TV is carried on the Web and on an MPEG-2 digital signal accessed via satelliteAMC-6, at 72 degrees west longitude, transponder 17C, 4040 MHz, vertical polariza-tion. It's available in Alaska and Hawaii on AMC-7, at 137 degrees west longitude,transponder 18C, at 4060 MHz, horizontal polarization. A Digital Video Broadcast com-pliant Integrated Receiver Decoder is required for reception. For NASA TV informationand schedules on the Web, visit: www.nasa.gov/ntv

Launch Media Credentialing

News media representatives who would like to cover the launch in person must beaccredited through the NASA Kennedy Space Center newsroom. Journalists may con-

tact the newsroom at 321/867-2468 for more information.

Briefings

An overview of the mission will be presented in a news briefing broadcast on NASATelevision originating from NASA Headquarters in Washington at 1 p.m. EDT July 21.Pre-launch briefings at Kennedy Space Center are scheduled at 1 p.m. and 2 p.m.EDT Aug. 8, 2005. Specific information about upcoming briefings, as they are sched-uled, will be kept current on the Internet at www.nasa.gov/mro

Internet Information

Extensive information on the Mars Reconnaissance Orbiter project including an elec-tronic copy of this press kit, press releases, fact sheets, status reports, briefing sched-ule and images, is available at www.nasa.gov/mro . More detailed information on themission is available at the Mars Reconnaissance Orbiter project website atmars.jpl.nasa.gov/mro

5


8/47

Quick Facts

OrbiterDimensions: Height 6.5 meters (21 feet) with 3-meter-diameter (10-foot) dish antenna;

width 13.6 meters (45 feet) with pair of 5.35- by 2.53-meter (17.56- by 8.30-foot)solar panelsMass: 2,180 kilograms (4,806 pounds) total at launch, consisting of 139 kilograms

(306 pounds) science payload, 892 kilograms (1,967 pounds) other dry weight,plus 1,149 kilograms (2,533 pounds) of propellant and pressurant

Power: 20 square meters (220 square feet) of solar panels providing 2,000 watts atmission's farthest point from the Sun, plus nickel-hydrogen batteries for periodswhen the panels are not in sunshine

Science instruments: Hyper-spectral imaging spectrometer, very-high-resolutioncamera, context camera, color camera, climate sounder, shallow subsurfaceradar

Launch VehicleType: Atlas V-401 (two-stage Atlas booster with Centaur upper stage)Height with payload: 57.4 meters (188 feet)Mass fully fueled: 333,000 kilograms (730,000 pounds)

MissionLaunch location: Pad LC-41, Cape Canaveral Air Force Station, FloridaLaunch period: August 10 to September 5, 2005Earth-Mars distance on August 10, 2005: 116 million kilometers (72 million miles)Mars arrival: March 10 to March 16, 2006 (depending on launch date)Earth-Mars distance on March 10, 2006: 215 million kilometers (134 million miles)One-way speed-of-light time from Mars to Earth on March 10, 2006: 12 minutesTotal distance traveled, Earth to Mars: About 500 million kilometers (310 million miles)Aerobraking phase: March to October 2006Primary science phase: November 2006 to December 2008Orbit during science phase: Near-polar orbit at altitudes ranging from 255 kilometers

(158 miles) to 320 kilometers (199 miles); 112 minutes per orbitQuantity of planned science data return: 26 terabits or moreCommunications relay phase: January 2009 to December 2010 (mission extensions

possible)

ProgramCost: About $720 million total, consisting approximately of $450 million spacecraft

development and science instruments; $90 million launch; $180 million missionoperations, science processing and relay support for 5.5 years

6


9/47

Mars at a Glance

General

One of five planets known to ancients; Mars was Roman god of war, agriculture and thestate

Yellowish brown to reddish color; occasionally the third brightest object in the night sky afterthe Moon and Venus

Physical Characteristics

Average diameter 6,780 kilometers (4,212 miles); about half the size of Earth, but twice thesize of Earth's Moon Same land area as Earth, reminiscent of a rocky desert Mass 1/10th of Earth's; gravity only 38 percent as strong as Earth's Density 3.9 times greater than water (compared to Earth's 5.5 times greater than water) No planet-wide magnetic field detected; only localized ancient remnant fields in variousregions

Orbit

Fourth planet from the Sun, the next beyond Earth About 1.5 times farther from the Sun than Earth is Orbit elliptical; distance from Sun varies from a minimum of 206.7 million kilometers (128.4millions miles) to a maximum of 249.2 million kilometers (154.8 million miles); average distancefrom the Sun 227.7 million kilometers (141.5 million miles) Revolves around Sun once every 687 Earth days Rotation period (length of day) 24 hours, 39 min, 35 sec (1.027 Earth days) Poles tilted 25 degrees, creating seasons similar to Earth's

Environment

Atmosphere composed chiefly of carbon dioxide (95.3%), nitrogen (2.7%) and argon (1.6%) Surface atmospheric pressure less than 1/100th that of Earth's average Surface winds up to 40 meters per second (80 miles per hour) Local, regional and global dust storms; also whirlwinds called dust devils Surface temperature averages -53 C (-64 F); varies from -128 C (-199 F) during polar nightto 27 (80 F) at equator during midday at closest point in orbit to Sun

Features

Highest point is Olympus Mons, a huge shield volcano about 26 kilometers (16 miles) highand 600 kilometers (370 miles) across; has about the same area as Arizona Canyon system of Valles Marineris is largest and deepest known in solar system; extends

more than 4,000 kilometers (2,500 miles) and has 5 to 10 kilometers (3 to 6 miles) relief fromfloors to tops of surrounding plateaus

Moons

Two irregularly shaped moons, each only a few kilometers wide Larger moon named Phobos ("fear"); smaller is Deimos ("terror"), named for attributes per-sonified in Greek mythology as sons of the god of war

7


10/47

Where Weve Been and Where Were Going

Building on scientific discoveries and lessons learned from past and ongoing missions,NASA's Mars Exploration Program is working over many years to establish a sustained

observational presence both around and on the surface of Mars. This includes orbitersthat view the planet from above and act as telecommunications relays; surface-basedmobile laboratories; robots that probe below the planet's surface; and, ultimately, mis-sions that return soil and rock samples to Earth. With international cooperation, thelong-term program is guided by compelling questions that scientists are interested inanswering about Mars, developing technologies to make missions possible withinavailable resources. The program's strategy is to seek to uncover profound newinsights into Mars' past environments, the history of its rocks and interior, the roles andabundance of water and, quite possibly, evidence of past and present life.

As part of the NASA's Vision for Space Exploration, these missions of discovery fore-

see human exploration of the Moon, Mars and beyond in coming decades.

The following are the most recently completed, ongoing and near-term future Mars

missions of exploration by NASA and its international partners:

Mars Pathfinder (December 1996 - March 1998): The first completed mission inNASA's Discovery Program of low-cost, rapidly developed planetary missions withhighly focused scientific goals, Mars Pathfinder far exceeded its expectations and out-lived its primary design life. This lander, which released its Sojourner rover at theMartian surface, returned 2.3 billion bits of information, including more than 17,000images and more than 15 chemical analyses of rocks and soil and extensive data onwinds and other types of weather. Investigations carried out by instruments on both thelander and the rover suggest that Mars had liquid water on its surface and a thickeratmosphere. The lander and rover functioned far beyond their planned lifetimes (30days for the lander and seven days for the rover), but eventually, after about threemonths on the Martian surface, depletion of the lander's battery and a drop in the lan-der's operating temperature are thought to have ended the mission.

Mars Global Surveyor (November 1996 - present): During its primary mapping mis-sion from March 1999 through January 2001, NASA's Mars Global Surveyor collectedmore information than any other previous Mars mission. Today the orbiter continues to

gather data in a second extended mission. As of May 1, 2003, it has completed morethan 20,000 orbits of Mars and returned more than 137,000 images, 671 million laser-altimeter shots and 151 million spectrometer measurements. Some of the mission'smost significant findings include: evidence of possibly recent liquid water at the Martiansurface; evidence for layering of rocks that points to widespread ponds or lakes in theplanet's early history; topographic evidence that most of the southern hemisphere ishigher in elevation than most of the northern hemisphere, so that any downhill flow ofwater and sediments would have tended to be northward; identification of gray

8


11/47

hematite, a mineral suggesting a wet environment when it was formed; and extensiveevidence for the role of dust in reshaping the recent Martian environment. GlobalSurveyor provided valuable details for evaluating the risks and attractions of potentiallanding sites for the Mars Exploration Rover missions, and served as a communica-tions relay for the rovers during and after their landings.

Mars Climate Orbiter and Mars Polar Lander (1998-99): These NASA spacecraftwere both lost upon Mars arrival.

Mars Odyssey (April 2001 - present): This NASA orbiter's prime mapping missionbegan in March 2002. Its suite of gamma-ray spectrometer instruments has providedstrong evidence for large quantities of frozen water mixed into the top layer of soil inthe 20 percent of the planet near its north and south poles. By one estimate -- likely anunderestimate -- the amount of water ice near the surface, if melted, would be enoughwater to fill Lake Michigan twice. Odyssey's infrared camera system has also provideddetailed maps of minerals in rocks and soils. A layer of olivine-rich rock in one canyon

near Mars' equator suggests that site has been dry for a long time, since olivine is eas-ily weathered by liquid water. Nighttime infrared imaging by Odyssey's camera systemprovides information about how quickly or slowly surface features cool off after sunset,which gives an indication of where the surface is rocky and where it is dusty.Odyssey's observations helped evaluate potential landing sites for the MarsExploration Rovers, and relays via this orbiter have been the rovers' main way of send-ing information to Earth. About 90 percent of data from the rovers has been relayed viaOdyssey, which passes over each rover twice a day.

Mars Exploration Rover Spirit (June 2003 - present): Spirit and its twin,Opportunity, are mobile robotic field geologists sent to examine geological clues about

the environmental history, particularly the history of water, at carefully selected sites.Together, they make up NASA's Mars Exploration Rover Project. Spirit is exploringinside Gusev Crater, a bowl 150 kilometers (95 miles) in diameter. Orbital images sug-gest Gusev may have once held a lake fed by inflow from a large valley network thatchannels into the crater from highlands to the south. Spirit landed in January 2003 in alevel plain pocked with small craters and strewn with loose rocks. The rover found thatthe rocks on the plain are volcanic with slight alteration by exposure to water. By June2003, Spirit had driven to a range of hills about 2.6 kilometers (1.6 miles) from thelanding site in a quest for exposed bedrock. Exploring in the hills since then, Spirit hasfound an assortment of rocks and soils bearing evidence of extensive exposure towater, including the iron-hydrogen-oxide mineral goethite and sulfate salts.

Mars Exploration Rover Opportunity (July 2003 - present): This rover was sent toa flat region named Meridiani Planum, where the spectrometer on Mars GlobalSurveyor had discovered a large exposure of a type of hematite that usually, but notalways, forms in the presence of water. Opportunity landed inside a crater only 22meters (72 feet) in diameter and immediately saw exposed bedrock in the crater'sinner slope. During the next few weeks, the rover's examination of that outcrop settled

9


12/47

the long-running debate about whether Mars ever had sustained liquid water on its sur-face. Composition and textures showed that the rocks not only had been saturatedwith water, but had actually been laid down under gently flowing surface water. For sixmonths beginning in June 2003, Opportunity examined deeper layers of rock inside astadium-sized crater about 700 meters (half a mile) from the landing site. The rocks

had all soaked in water, but textures in some showed that periods of dry, wind-blowndeposition alternated with periods when water covered the surface. After examining itsown heat shield and a nickel-iron meteorite near this crater, Opportunity drove morethan 3 kilometers (2 miles) southward to reach a different type of terrain in search ofrocks with different information to add about the region's wet history.

Mars Express (2003): This is a European Space Agency orbiter with NASA partici-pation in two of its seven instruments. The spacecraft has been returning color imagesand other data since January 2004 after entering orbit in late December 2003. It hasconfirmed water ice in Mars' south polar cap and added information about how thesolar wind has been removing water vapor from Mars' atmosphere for billions of years.

Mars Express has found traces of methane in Mars' atmosphere. Scientists proposethat this gas would break down rapidly enough to be undetectable if there is not anactive source, either biological or non-biological, maintaining the amount. The orbiterhas also mapped variations in the concentration of water vapor in the lower portion ofthe atmosphere. The spacecraft's June 2005 deployment of the antenna for a ground-penetrating radar instrument prepares for a search for layers bearing ice and possiblywater beneath the surface of Mars.

Phoenix Mars Scout (2007): The first in a planned series of competitively selectedNASA Mars Scout missions, Phoenix will land in icy soils near the north polar ice capof Mars and explore the history of the water in these soils while checking for organic

chemicals and monitoring polar climate. It is scheduled to launch in August 2007 andland in May 2008. The stationary lander will operate for up to three months. Its roboticarm is designed to dig a trench up to half a meter (20 inches) deep and deliver sam-ples from it to an onboard laboratory to analyze the samples' chemistry and physicalproperties. The mission will serve as NASA's first exploration of this ice-rich region andrenew the search for carbon-bearing compounds, last attempted by the Viking landersof the 1970s. The Phoenix mission plan, developed by a team led by a University ofArizona scientist, was one of 25 proposals submitted to become the first Mars Scoutmission. NASA selected Phoenix from among four finalist proposals in 2003. A majorrole for Mars Reconnaissance Orbiter in 2008 will be to serve as the primary communi-

cations relay for Phoenix.

Mars Science Laboratory (2009): This NASA mission will use precision landingtechnologies to put a roving science laboratory at a selected site on Mars with a pay-load of science instruments more than 10 times as massive as those of earlier Marsrovers. The laboratory is designed to operate for more than a Martian year (687 Earthdays) and travel across a much greater range than previous rovers. To help scientistsassess whether the landing area ever had or still has environmental conditions favor-

10


13/47

able to microbial life, the rover will analyze dozens of samples scooped from the soiland cored from rocks. Instruments have been selected that could identify and inventorythe chemical building blocks of life in the samples and identify features that may showeffects of biological processes. The mission will mark major advances in measurementcapabilities and surface access. It will demonstrate technologies for accurate landing

that will be necessary for sending later missions to sites that are scientifically com-pelling but difficult to reach.

Additional Mars Scouts (2011 and later): Mars Scouts are competitively proposedmissions intended to supplement and complement, at relatively low cost, the core mis-sions of NASA's Mars Exploration Program. Phoenix is the first. The next round of pro-posals and selection targets a launch no sooner than 2011.

Beyond 2011: For the second decade of this century, NASA proposes additionalmissions to examine the geological record and current environment at selected siteson Mars, possibly including extended surface operations, deep-drilling or the first mis-

sion to return samples from Mars. The flexible program includes many options.Scientists and mission planners foresee technology development providing advancedcapabilities, such as life-detection investigations, drilling to reach underground sites, aMars ascent vehicle and a rendezvous in Mars orbit.

In support of the Vision for Space Exploration, NASA has also begun preparationsfor sending human explorers to Mars and beyond. An early step in realizing the visionwill be development of a crew exploration vehicle in the next few years; a crucial inter-mediate step will be return of astronauts to the Moon by 2020, this time for a sustainedpresence there. Meanwhile, plans envision precursor robotic missions to Mars between2011 and 2020 that will pave the way for human exploration there by examining the

challenges to human missions and demonstrating solutions. Some challenges thatastronauts will face are environmental factors, such as dust and radiation. Others aretechnological requirements, such as reliable precision landing and an adequate energysupply.

11


14/47

Science Investigations

Water is a key to at least four of the most critical questions about Mars: Has Mars hadlife? Could Mars support human outposts? Can Mars teach us helpful information

about climate change? Do Mars and Earth share the same geological processes?

Water is a prerequisite for life, a potential resource for human explorers and a majoragent of climate and geology. That's why NASA has pursued a strategy of "follow thewater" with spacecraft sent to Mars in recent years, resulting in discoveries such asfresh gullies carved by fluid, copious ice mixed into the top layer of surface materialand ancient rock layers formed under flowing water.

The Mars Reconnaissance Orbiter mission will follow the water further. The string ofwater-related discoveries by spacecraft currently at Mars leave many questions thatthis orbiter is well equipped to investigate. We now know there was standing water on

the planet. How extensively? How long? How often? Where did it well up from under-ground and where did it flow down from uphill drainage networks?

Deciphering the relationships among today's layers of material at and near the surfacewill help scientists answer these questions and raise new ones. For example, MarsReconnaissance Orbiter may be able to resolve whether layers seen in the walls ofcanyons such as Valles Marineris are pasted on from the slumping of walls abovethem, as they might be if water emerged from the walls, or exposures of underlyinglayers emplaced before the deepening of the canyon cut through them, like inArizona's Grand Canyon. How large an area and how long a period is evidenced in thewater-related layers around Opportunity's landing site in Meridiani Planum?Observations by Mars Reconnaissance Orbiter may improve estimates of the answersby tracing the edges of layers and following where one extends beneath another.

Mars has shown surprises each time researchers have used increased resolution toexamine it. The surface bears diversity in mineral composition and physical structuredown to the smallest scales discernable from orbit so far. Researchers anticipate thatthe considerably higher resolution and coverage possible with Mars ReconnaissanceOrbiter will reveal more. For example, the mission might find deposits of water-relatedminerals that don't cover enough ground to be detected by previous orbiters.

Science Objectives

Since its early planning stages, the Mars Reconnaissance Orbiter mission has hadthree underlying science objectives:

1. Advance our understanding of Mars' current climate, the processes that haveformed and modified the surface of the planet, and the extent to which waterhas played a role in surface processes.

12


15/47

2. Identify sites where possible effects of liquid water indicate environments thatmay have been conducive to biological activity or might even now harbor life.

3. Identify and characterize sites for future Mars landings.

In pursuit of these objectives, the mission will make observations and measurementsto:

Assess Mars' seasonal and time-of-day variations in water, dust and carbondioxide in the atmosphere.

Characterize Mars' global atmospheric structure and surface changes. Search for sites with evidence of water or hydrothermal activity. Examine the detailed stratigraphy (layers laid down over time), geologic

structure and composition of Mars' surface features. Probe beneath the surface for evidence of subsurface layering, reservoirs of

water or ice, and the internal structure of polar ice caps. Map and monitor the Martian gravity field to improve knowledge about Mars'

crust and variations in atmospheric mass. Identify and characterize prospective landing sites with high potential for

discoveries by future missions.

Research Strategy

The orbiter will use a wide range of wavelengths for its investigations, from ultravioletthrough visible and infrared to short-wave radio. It will see Mars' surface in greater

detail than any previous Mars orbiter.

The tremendous amount of data generated by observations in many wavelengths andat high resolutions dictates the importance of the orbiter's large high-gain antenna andhigh-powered telecommunications system for sending the data to Earth. Nevertheless,limits on time and data capacity mean that only a small fraction of Mars can be exam-ined at the highest resolution. The surface of Mars covers an area about the same asall the dry land on Earth. Surprises detectable with this orbiter's capable instrumentscould lie anywhere. Choosing where to look closely will affect what discoveries aremade.

To make the most effective use of the highest-resolution capabilities, the mission's sci-ence team will employ a strategy of mixing three distinct modes of observations: dailyglobal-scale monitoring, regional surveys and targeted high-resolution observations.The broader views will aid interpretation of the higher-resolution data and will identifyadditional sites for targeted observations. Some instruments can observe in more thanone mode. Targeted observations may combine nearly simultaneous data collection bymore than one instrument, providing context for interpreting each other's data.

13


16/47

Science Instruments

Mars Reconnaissance Orbiter will carry six science instruments. Two additional investi-gations will use the spacecraft itself as an instrument.

The High Resolution Imaging Science Experiment will photograph selectedplaces on Mars with the most powerful telescopic camera ever built for use at a foreignplanet. It will reveal features as small as a kitchen table in images covering swaths ofMars' surface 6 kilometers (3.7 miles) wide. Combining images taken through filtersadmitting three different portions of the spectrum will produce color images in the cen-tral portion of the field of view. Paired images of top-priority target areas taken fromslightly different angles during different orbits will yield three-dimensional views reveal-ing differences in height as small as 25 centimeters (10 inches).

Of the orbiter's three research modes (global monitoring, regional survey and targetedobservations), this instrument's role will be in the targeted-observation mode.

Researchers will use the high-resolution camera to examine shapes of deposits andother landforms produced by geologic and climatic processes. As one example, theywill look for boulders in what appear to be flood channels, which would be evidencethat the channels were cut by great flows of water, rather than glaciers or lava flows.And they will check the scale of layering in polar deposits. Those layers are believed toresult from cyclical variations in Mars' climate; their thickness could be an indication ofthe time scale of climate cycles. Some layers are at least as thin as the current limit ofresolution in orbital images, so higher-resolution imaging will add more information fordeciphering climate history. Other anticipated targets include gullies, dunes and pat-terned ground.

This camera has a primary mirror diameter of 50 centimeters (20 inches) and a field ofview of 1.15 degrees. At its focal plane, the instrument holds an array of 14 electronicdetectors, each covered by a filter in one of three wavelength bands: 400 to 600nanometers (blue-green), 550 to 850 nanometers (red), or 800 to 1000 nanometers(near infrared). Ten red detectors are positioned in a line totaling 20,028 pixels acrossto cover the whole width of the field of view. Two each of the blue-green and near-infrared detectors lie across the central 20 percent of the field. Pixel size in imagestaken from an altitude of 300 kilometers (186 miles) will be 30 centimeters (12 inches)across, about a factor of two better than the highest-resolution down-track imagingpossible from any earlier Mars orbiter and a factor of five better than any extended

imaging to date. As a rule of thumb, at least three pixels are needed to show the shapeof a feature, so the smallest resolvable features in the images will be about a meter (3feet) across for an object with reasonable contrast to its surroundings. The instrumentuses a technology called time delay integration to accomplish a high signal-to-noiseratio for unprecedented image quality.

Dr. Alfred McEwen of the University of Arizona, Tucson, is the principal investigator forthe High Resolution Imaging Science Experiment. Ball Aerospace, Boulder, Colo., built

14


17/47

the instrument for the university to provide to the mission. Additional information aboutthe instrument is available at hirise.lpl.arizona.edu .

The Compact Reconnaissance Imaging Spectrometer for Mars will extend thesearch for water-related minerals on Mars by providing spectra that can be used to

identify the mineral composition of the surface. Each spectrum will indicate measure-ments of the amount of light that Mars surface materials reflect or emit in many differ-ent wavelengths, or colors, of visible and infrared light. Most minerals expected in theMartian crust, and especially those formed by water-related processes, have charac-teristic fingerprints in spectra of these wavelengths. The spectrometer will collect infor-mation that could find key minerals in patches as small as a house, using resolutionabout 10 times sharper than in any previous look at Mars in infrared wavelengths andsharp enough to discover a deposit left by an individual hot spring or evaporated pond,if such deposits exist.

The imaging spectrometer will work both in targeted and survey modes. It will target a

few thousand selected areas for inspection at highest spatial resolution -- 18 meters(60 feet) per pixel -- and spectral resolution -- 544 different wavelengths. It will spendmore of its time surveying the entire planet at resolutions of 100 to 200 meters (330 to660 feet) per pixel in and about 70 different spectral channels ("colors"). The surveywill find candidate sites for targeted inspection. The search for water-related mineralssuch as carbonates, clays and salts gets top priority for use of this instrument.Researchers are planning observations of sites such as smooth interiors of ancientcraters that may have held lakes and volcanic regions that may have produced hotsprings. They will also use the spectrometer to monitor seasonal changes in dust andice particles suspended in the atmosphere.

The spectrometer has a telescope with a 10-centimeter (4-inch) aperture and a 2-degree field of view. That field of view produces images of swaths of Mars' surfaceabout 10 kilometers (6 miles) wide. The instrument records the intensities of light in arange of wavelengths from 370 nanometers (violet) to 3,940 nanometers (nearinfrared) and divides that range into bands as small as 6.55 nanometers wide. It ismounted on a gimbal, which allows it to follow a target on the surface as the orbiterpasses overhead.

The principal investigator for the Compact Reconnaissance Imaging Spectrometer forMars is Dr. Scott Murchie of the Johns Hopkins University Applied Physics Laboratory,

Laurel, Md., which provided the instrument. Additional information about the spectrom-eter is available at crism.jhuapl.edu .

The orbiter's Context Camera will return images of swaths 30 kilometers (18.6miles) wide. Many of its images will be centered on the narrower swaths being imagedsimultaneously by the high-resolution camera or the imaging spectrometer, or both. Ithas a resolution capable of showing the shapes of features smaller than a tennis court.

15


18/47

This instrument will perform roles in both the regional-survey and the targeted-observa-tion modes. For the targeted mode, it will provide broad yet detailed visual context forinterpreting observations by co-targeted instruments. Over the course of the primaryscience mission, it will produce regional surveys of about 15 percent of the planet'ssurface in relatively high resolution, which is expected to identify many targets for more

detailed inspection. However, its ability to provide extended area imaging at moderate-ly high resolution will enable it to examine the stratigraphy and morphology of manyregional features and thus directly address key questions about changes in the Martiansurface over geologic time and the roles that water and wind have played in thesechanges.

The camera is monochromatic and will produce black-and-white images. It has a singlepassband for visible light at 500 to 700 nanometers). It has a 5.8-degree field of viewrecorded onto a linear array 5,000 pixels wide, providing a resolution of 6 meters (20feet) per pixel.

Malin Space Science Systems, San Diego, Calif., provided the Context Camera for thismission. Dr. Michael Malin is team leader for use of the instrument.

Mars Color Imager will produce daily global views to monitor changes in the atmos-phere and on the surface. It can produce color images and see in ultraviolet wave-lengths. Each image through the extremely wide-angle lens will catch the planet fromhorizon to horizon with spatial resolution selectable from one kilometer (0.6 mile) perpixel to 10 kilometers (6 miles) per pixel.

As a key instrument for the mission's global-monitoring mode, Mars Color Imager will

provide daily weather maps of the entire planet and will track surface changes, such asthe seasonal growing and shrinking of polar frosts and the movement of dust at otherlatitudes. Use of color filters will also enable researchers to identify the composition ofclouds, which may be water ice, carbon-dioxide ice, or dust. Researchers will makeuse of the camera's ultraviolet filters to examine variations in the amount of ozone inthe atmosphere. Ozone serves as a reverse indicator about water in Mars' atmos-phere. Where there's more water, there's less ozone, and vice versa.

Mars Color Imager is essentially a copy of a camera that flew on the lost Mars ClimateOrbiter mission. However the instrument on Mars Reconnaissance Orbiter has a widerfisheye lens to compensate for planned spacecraft rolls needed to target specific sites

on Mars with other instruments. The camera has a field of view of 180 degrees. Itsseven filters include five centered in visible-light wavelengths (425, 550, 600, 650 and725 nanometers) and two in ultraviolet wavelengths (250 and 320 nanometers).

Malin Space Science Systems, San Diego, Calif., provided this instrument, and Dr.Michael Malin of that company is the principal investigator for it.

16


19/47

Mars Climate Sounder will study water vapor, dust, ices and temperatures in Mars'atmosphere. It will assess how they vary with altitude, map how they are distributedaround the planet, and monitor their changes from day to night and from season toseason. The results will aid understanding of the atmosphere's structure and circula-tion, thus the planet's weather and climate. The instrument looks both toward the hori-

zon and straight down, in a broadband visible and in several thermal infrared channels.Looking toward the horizon, it can observe the atmosphere in vertical slices, assessingeach 5-kilometer-thick (3-mile-thick) section from the surface to an altitude of 80 kilo-meters (50 miles). The resulting atmospheric profiles from different areas around theplanet can be combined into daily, three-dimensional global weather maps for bothdaytime and nighttime.

Mars Climate Sounder is one of the instruments serving the mission's global-monitor-ing research mode. One goal for researchers using it is to examine how solar energyinteracts with the atmosphere and the surface. The measurements will also serveunderstanding of how the atmosphere moves water around the planet seasonally and

the give and take between the surface and the atmosphere in quantities of water anddust. One area of regional focus is the polar regions, where measurements of theamount of solar energy absorbed by the surface ice can be used to estimate theamount of carbon dioxide that is exchanged between the atmosphere and the surfaceduring the Martian year.

The Mars Climate Sounder instrument will address the scientific goals of an earlier,much heavier instrument that flew on the ill-fated Mars Observer and Mars ClimateOrbiter spacecraft. It uses a pair of telescopes with apertures of 4 centimeters (1.6inches). They are mounted in a cylinder in a yoke frame articulated so that, without

repositioning the spacecraft, the telescopes can point sideways to the horizon and tospace, down onto the planet, or at calibration targets attached to the yoke. Detectorsrecord the intensity of radiation in nine channels or bands of the electromagnetic spec-trum. One channel covers visible and near-infrared frequencies from 300 to 3,000nanometers (0.3 to 3 microns). The other eight channels are in the thermal infraredpart of the spectrum, from 12 to 50 microns.

Principal investigator for the Mars Climate Sounder is Dr. Daniel McCleese of NASA'sJet Propulsion Laboratory, Pasadena, Calif., and JPL provided the instrument to themission.

The orbiter's Shallow Subsurface Radar will probe beneath Mars' surface to findand map underground layers of ice, rock and, if present, liquid water. The informationwill come from the patterns of reflected radio waves transmitted by the instrument. Theinstrument will search to a depth of up to one kilometer (0.6 mile), with the actualdepth of penetration depending on the composition of the upper crust of Mars. It will beable to distinguish between layers of different composition or physical state (e.g., liquidwater) as thin as 10 meters (33 feet).

17


20/47

The Shallow Subsurface Radar is a regional-survey instrument. Researchers will use itto follow up on the discovery by Mars Odyssey that the top layer of ground in manyparts of Mars holds substantial quantities of hydrogen, believed to be in the form ofwater ice. The Odyssey instruments provided information about the top meter (3 feet)of ground. This radar will allow scientists to determine whether the ice-bearing material

extends much deeper, helping scientists discern whether the ice content results froman equilibrium with the Martian atmosphere of today or persists as a remnant of amuch thicker ice layer formed long ago. The instrument can distinguish icy layers fromwater-bearing layers. If the instrument does find any underground water, those sitescould become landing-site candidates for future Mars rovers or human exploration.Researchers also plan to use the Shallow Radar for mapping the distribution of buriedchannels, studying the internal structure of Mars' ice caps, checking for liquid waterunderneath the ice caps, and examining the extent and relative depths of rock layers inselected regions. The structure of the upper crust may be very complex and so the useof surface observations may be critical to the proper interpretation of the radar data.Thus, areas like the Meridiani Planum region surrounding the rover Opportunity's

research area are high-priority targets for radar mapping to see how far the surfacelayers with their water-related minerals extend laterally beneath the surface.

The instrument will transmit "chirps" lasting 85 milliseconds each at radio frequenciesfrom 15 megahertz to 25 megahertz (wavelengths of about 15 meters or 50 feet in freespace) with 10 watts of power. In most cases, it will operate on the night side of theplanet. Compared with the only other ground-penetrating radar instrument ever to orbitMars, the Mars Advanced Radar for Subsurface and Ionospheric Sounding on theEuropean Space Agency's Mars Express, the instrument on Mars ReconnaissanceOrbiter will focus on shallower layers and have higher resolution. The Shallow

Subsurface Radar's antenna will extend five meters (16 feet) to each side of thespacecraft. It is stowed in a folded-up configuration for launch and will not be deployeduntil after aerobraking has been completed. During the mission's two-year primary sci-ence phase, investigations with the Shallow Subsurface Rader are expected to returnmore data than the entire NASA Magellan mission, which mapped 99 percent of thesurface of Venus with an orbiting radar instrument in the early 1990s.

The Italian Space Agency (ASI) selected Alenia Spazio, Rome, as the prime contractorfor the Shallow Subsurface Radar and selected Dr. Roberto Seu of the University ofRome La Sapienza as the principal investigator for the instrument's science team. TheItalian Space Agency provided the Shallow Subsurface Radar to NASA as a facility sci-

ence instrument, with Dr. Seu as team leader. As part of this international collaboration,NASA selected a team of U.S. co-investigators, led by Dr. Roger Phillips of WashingtonUniversity, St. Louis, to support Dr. Seu's team.

Two additional facility science investigations will use spacecraft subsystems to conductscientific investigations of Mars.

18


21/47

The Gravity Investigation will track variations in the orbiter's movement during theprimary science phase of the mission in order to map the effects of variations in Mars'gravity on the spacecraft. Gravity provides information on the distribution of mass onand below the surface. Previous orbiters have identified variations in the planet's gravi-ty that result from regional differences in crustal thickness, seasonal changes in polar

caps and other factors. This spacecraft will yield higher-resolution data because it willbe orbiting at a lower altitude, about 30 percent closer to the planet than Mars GlobalSurveyor or Mars Odyssey. This will allow smaller features on the surface to beresolved in gravity maps.

Researchers will use the gravity measurements to study the processes that led to for-mation of surface features. They expect to study the thinning of the crust beneath theValles Marineris rift zone, to map how volcanic material accumulated beneath thelargest volcanoes and to see how impact structures modified the early Martian crust.They also anticipate that the data will reveal tiny changes in mass distribution as car-bon dioxide moves from the surface to the atmosphere and back again. (In its frozen

form, carbon dioxide is known as dry ice.) From changes in mass revealed by thegravitational effect on the spacecraft, scientists expect to measure how much dry-icesnow falls at high latitudes in the winter. These measurements will contribute to under-standing the weather and climate on Mars.

Team leader for this investigation is Dr. Maria Zuber of the Massachusetts Institute ofTechnology, Cambridge, and NASA's Goddard Space Flight Center, Greenbelt, Md.

The Atmospheric Structure Investigation will measure the vertical structure ofMars' upper atmosphere using sensitive accelerometers throughout the aerobraking

phase of the mission. The rate at which the spacecraft is slowed by atmospheric fric-tion (or drag) is proportional to the density of the air encountered. Thus, the upperatmosphere's effect on the spacecraft's velocity will be analyzed for information aboutchanges in the density of the atmosphere on each of more than 500 orbits, at altitudessometimes as low as 95 kilometers (59 miles) and possibly as high as 200 kilometers(124 miles). The information will guide safe aerobraking because knowledge of thechanging upper atmosphere is critical for avoiding excessive friction that would over-heat the spacecraft. This investigation will also contribute directly to the mission's sci-ence results, particularly regarding the major question of where Mars' ancient waterhas gone.

From the vertical structure of atmospheric density, scientists can determine atmospher-ic temperature and pressure. These may be clues to the fate of the water that wasclearly on the Mars surface billions of years ago. One possibility is that water mole-cules are broken up by solar radiation into atomic hydrogen and oxygen, with thehydrogen escaping into outer space; another possibility is that some of the water isunderground. The Atmospheric Structure Investigation will address the first possibility,loss of water via the escape of hydrogen to outer space. If the upper atmosphere iswarm enough, some of the hydrogen atoms would have enough energy to escape the

19


22/47

planet. Determining the density and temperature of the atmosphere will improve esti-mates of this loss process.

Other information about Mars atmosphere could also come from this investigation, justas discoveries resulted from the team's similar accelerometer measurements during

aerobraking phases of the earlier Mars Global Surveyor and Mars Odyssey missions.The Global Surveyor investigation determined that even intermediate-size dust stormsin the southern hemisphere immediately produced threefold increases of density in thenorthern hemisphere at aerobraking altitudes. These increases could have put the mis-sion at risk if the spacecraft had not been raised to a higher altitude. The team alsodiscovered enormous planetary-scale waves in density, which could also put thespacecraft at risk. Investigators developed techniques to predict when the spacecraftwould fly through the peaks and valleys of these waves to establish safe aerobrakingaltitudes. During Odyssey's aerobraking, the team discovered "winter polar warming"near the north pole of Mars at high altitudes. North polar Martian winter atmospherictemperatures were warmer than expected by about 100 degrees Kelvin (180 degrees

Fahrenheit). Mars Reconnaissance Orbiter's Atmospheric Structure investigators willsearch for similar winter warming near the south pole.

A new electronics design by Honeywell is expected to improve the signal-to-noise ratioof the Mars Reconnaissance Orbiter's accelerometers by more than a factor of 100over the accelerometers on Mars Odyssey. This should allow measurements to bemade at much higher altitudes than in the past, substantially improving estimates ofthe environment where hydrogen may escape. The investigation should also establishthe nature of atmospheric changes due to variations in altitude, latitude, season,time-of-day, Mars-Sun distance, meteorological activity, dust storm activity, and solar

activity.

Dr. Gerald Keating of George Washington University, Washington, is the team leaderfor this investigation.

20


23/47

Technology Objectives

The mission objectives for Mars Reconnaissance Orbiter do not end with the space-craft's scientific discoveries. It also has important work to do in relaying communica-

tions from robots on Mars' surface and in demonstrating communication and navigationtechnologies for use by future missions. Three instruments in the payload serve thesepurposes:

Electra is a technology package enabling Mars Reconnaissance Orbiter to act as anavigational and communications aid for other spacecraft as they approach Mars andoperate on the surface of Mars. It will use ultra-high frequency radio for relaying com-mands from Earth to stationary and mobile robots on the surface and for receiving sci-ence and engineering data to be relayed back to Earth via the orbiter's main antenna.As spacecraft with compatible systems approach Mars, signals from theReconnaissance Orbiter's Electra will provide information about the arriving space-

craft's speed and distance relative to Mars, allowing improved precision in landing.Similarly, Doppler data from Electra communications, coupled with information aboutthe orbiter's position, can accurately indicate the position of a stationary lander or arover on the surface.

If either or both of the Mars Exploration Rovers Spirit and Opportunity are still operat-ing in the late 2006, they could be the first surface robots to use Mars ReconnaissanceOrbiter as a communications relay. The navigation and communications strategies forthe Phoenix Mars Scout mission, scheduled for launch in 2007, are being developed totake advantages of the capabilities of Electra. Phoenix is slated to arrive at Mars inMay 2008 and land at a site in the arctic plains.

The Optical Navigation Camera is part of a technology demonstration of a naviga-tion technique. The demonstration will compare the predicted positions of Mars' twomoons, Phobos and Deimos, with this camera's observations of the moons as thespacecraft approaches Mars. While this technique is not necessary for MarsReconnaissance Orbiter's own navigation, the demonstration will prepare the way forrelying on it for navigating precise arrivals for future missions that land on Mars. Thecamera has an aperture of 6 centimeters (2.3 inches) and a narrow field of view of 1.4degrees.

The Ka Band Telecommunications Demonstration will allow comparison of theshorter-wavelength Ka radio band with the X band that is the standard for interplane-tary spacecraft communication with Earth and the primary band for this mission. TheKa band equipment uses less power than its X-band counterpart to send the sameamount of data. However, Ka band transmissions are more susceptible to being dis-rupted by water in Earth's atmosphere. Mars Reconnaissance Orbiter will use bothbands for sending data to Earth, providing a comparison that will aid planning of com-munication systems for future interplanetary missions.

21


24/47

Mission Overview

NASA's Mars Reconnaissance Orbiter will put a large, capable spacecraft into a low-altitude orbit around Mars for two years dedicated to examining the planet in unprece-

dented detail and, at least, an additional two years of providing communications-relaysupport for other missions. Before the primary science phase and the relay phase, themission must execute four challenging phases to get where it needs to be to do its job:the launch phase of a few hours, the cruise phase of about five months, the approachand orbit insertion phase of about two months, and the aerobraking phase of four to sixmonths.

Launch Vehicle

A two-stage Atlas V-401 launch vehicle will lift Mars Reconnaissance Orbiter fromSpace Launch Complex 41 at Cape Canaveral Air Force Station, Fla., and put the

spacecraft on a course toward Mars. The spacecraft's large payload of science instru-ments and, even more, the high-capacity telecommunications system needed to han-dle the huge flow of data from high-resolution instruments, add up to a heavy space-craft and the need for a powerful launch vehicle. The Atlas V-401, provided byLockheed Martin Space Systems, Denver, was selected through a competitive procure-ment process.

The first stage, or booster, of the Atlas V-401 will combust 284,089 kilograms (313tons) of fuel and oxidizer in just over four minutes within a single, throttlable engine --model RD-180, supplied by Russia -- with two thrust chambers. The kerosene-like fuel(type RP-1) and liquid oxygen will be loaded shortly before launch into cylindrical tanksthat make up most of the vehicle's height. The booster engine will provide thrust total-ing about 4 million newtons (900,000 pounds).

The second stage, connected with two interstage adaptors, is a Centaur upper stage.Its single, restartable engine -- model RL-10, from Pratt & Whitney Space Propulsion,West Palm Beach, Fla. -- uses liquid hydrogen and liquid oxygen and can provide upto 99,200 newtons (22,300 pounds) of thrust. The Centaur can control its orientationprecisely. This ability is important both to control the direction of thrust during theengine burns and also to prevent sunlight from shining directly into the spacecraft cam-eras and sensors that would be damaged by such intense light.

A payload adaptor connects the orbiter to the Centaur. This structure is about 1.2meters (47 inches) in diameter. It provides an electrical interface through which theorbiter communicates with the launch vehicle, and thus to ground crews, before andduring the launch. A releasable clamp band attaches the orbiter to the Centaur. When itis released, push-off springs separate the two.

The spacecraft will ride aloft inside a protective fairing atop the Centaur stage. The fair-

22


25/47

ing, or nose cone, is 4 meters (13 feet) in diameter. With the fairing on top, the vehicleready for launch will stand 57.4 meters (188 feet) tall.

The first Atlas V was launched in August 2002. Mars Reconnaissance Orbiter will bethe first interplanetary spacecraft launched on an Atlas V, and the first on any of the

Atlas series since Pioneer Venus in May 1978. However, the Atlas series, with morethan 580 launches since the first in 1957, served frequently in the lunar and interplane-tary missions of the 1960s and '70s. An Atlas launched the very first successful mis-sion to Mars, NASA's Mariner 4, on Nov. 28, 1964.

Launch Timing

As Earth and Mars race in circles around the Sun, with Earth on the inside track, Earthlaps Mars about every 26 months. The two planets come relatively close together atthat point, which is called an opposition because Mars is temporarily on the oppositeside of Earth from the Sun. The best time to launch a mission to Mars, in terms of how

much energy is required for the trip, is a few months before that happens. NASA hasused every one of these Mars launch opportunities since 1996 and plans to use futureones indefinitely. The next Mars opposition will be Nov. 7, 2005. Not all Mars opposi-tions are the same, because the two planets' orbits are elliptical, not circular.

During the 2005 opposition period, the closest approach of the two planets will be onOct. 30, when they will be 69.42 million kilometers (43.1 million miles), about 24 per-cent farther than during the 2003 opposition. That distance, the launch vehicle's power,the spacecraft's weight, and the desired geometry of approach to Mars are all factorsin determining the range of possible launch dates. The period begins on Aug. 10,

2005, and lasts 21 days, through Aug. 30, 2005.

The window of possible launch times on the first day of the launch period will begin at7:54 a.m. Eastern Daylight Time and last for two hours. The length of the window onthe other 20 days ranges from 30 minutes to two hours.

Launch Sequences

Between ignition and liftoff, the booster engine will ramp quickly to an initial throttle set-ting of 75 percent. Before the vehicle clears its own height, the engine will throttle up to92 percent. The throttle settings vary by launch date for most of the remaining burn

until the booster engine shuts off four minutes after liftoff. Ten seconds before cutoff,engine will throttle back to about 50 percent. By the time of booster-engine cutoff, thelaunch vehicle will be about 300 kilometers (186 miles) downrange at an altitude of101 kilometers (63 miles).

Ten seconds after booster-engine cutoff, the Centaur upper stage, with payloadattached, will separate from the depleted first stage. The first stage will fall into theAtlantic Ocean. Nine seconds after separation, the Centaur's engine will ignite, and a

23


26/47

few seconds after that, the vehicle will shed the fairing that has shielded the payload tothis point. The Centaur engine's first burn will last 9 minutes and 35 seconds, deliver-ing the spacecraft and upper stage into a parking orbit around Earth and cutting off atabout 13 minutes after liftoff. At this point the spacecraft will be about 3,200 kilometers(approximately 1,990 miles) downrange at an altitude of 185 kilometers (115 miles).

The shape of the planned parking orbit is an ellipse varying in altitude from 148 kilome-ters (92 miles) to 185 kilometers (115 miles). However, the spacecraft will not completeeven one orbit. The Centaur engine will start its second burn anywhere from 33 to 55minutes after its first cutoff, depending on launch date. This burn will last about 5 min-utes and 29 seconds, lofting the spacecraft out of Earth orbit and on its way towardMars. Six minutes after the Centaur engine's second cutoff, the second stage releasesthe clamp that attaches the Mars Reconnaissance Orbiter. By that point, not quite anhour after liftoff, the two-stage Atlas V will have accelerated the spacecraft to about11,000 meters per second (25,000 miles per hour). Shortly after that, the separatedCentaur performs its last maneuver, taking itself out of the orbiter's flight path to avoid

colliding with the orbiter or flying to Mars.

Once the orbiter has separated from the upper stage of the launch vehicle, it will unfoldits two solar-array panels from their stowed configuration. The spacecraft will be on thenight side of Earth when this happens, so it will still be running on batteries until it getsback into sunlight, 20 to 30 minutes after separation. Deployment and pointing of thehigh-gain antenna, a dish 3 meters (10 feet) in diameter, will follow deployment of thesolar arrays.

Interplanetary Cruise

The trip from Earth to Mars will take about seven months, with arrival on March 10,2006. For planning purposes, project managers consider the cruise phase as begin-ning about three days after launch and ending two months before Mars arrival. Mainactivities during cruise include daily monitoring of orbiter subsystems, navigation activi-ties to determine and correct the vehicle's flight path, as well as checkout and calibra-tion of spacecraft subsystems and science instruments.

During cruise, the spacecraft will keep its solar arrays facing the Sun and will periodi-cally adjust its high-gain antenna to maintain communications with Earth.

Five trajectory correction maneuvers are planned during the trip. The first and largestis scheduled 15 days after launch, and will use the orbiter's most powerful 170-newtonthrusters. Up until that point, the spacecraft's flight path will have been intentionallybiased slightly off-course to prevent the Centaur upper stage from following the space-craft and hitting Mars. This is an extra precaution in addition to the Centaur's final colli-sion-avoidance maneuver after separation from the orbiter.

The rest of the trajectory correction maneuvers will use the spacecraft's intermediate-

24


27/47

power, 22-newton thrusters instead of the more powerful set. All the maneuvers,including the first, will also use smaller, 0.9-newton thrusters to provide attitude controlduring the change in velocity.

The second trajectory maneuver is scheduled Nov. 17, or 99 days after the opening ofthe launch period. The third and fourth maneuvers are 40 days and 10 days beforearrival at Mars. The last scheduled maneuver is a contingency activity to be performedonly if needed. It can be conducted as early as 24 hours before orbit insertion and aslate as six hours before orbit insertion.

The calculations for trajectory corrections are based on very accurate determinations

25

Flight path


28/47

of the spacecraft's position, direction of movement and velocity. The MarsReconnaissance Orbiter mission will combine two traditional tracking techniques with anewer triangulation method to improve navigational precision. One of the traditionalmethods is ranging, which measures the distance to the spacecraft by timing preciselyhow long it takes for a radio signal to travel to the spacecraft and back. The other is

Doppler, which measures the spacecraft's speed relative to Earth by the amount ofshift in the pitch of a radio signal from the craft.

The newer method, called delta differential one-way range measurement, adds infor-mation about the location of the spacecraft in directions perpendicular to the line ofsight. Pairs of antennas at Deep Space Network sites on two different continents simul-taneously receive signals from the spacecraft, then the same antennas are used toobserve natural radio waves from a known celestial reference point, such as a quasar.

Other important events during the cruise stage will put various systems and instru-ments into final working order. Among these tasks are calibrations and alignments of

antennas, cameras and reaction-control thrusters. Camera checks will include imagingof Earth's Moon and the star Omega Centauri. The Electra ultra-high-frequency com-munications system will be tested in a link with a ground station at Stanford, Calif.Other tests will assess electromagnetic interference among spacecraft systems andinstruments in the space environment, and for jitter disturbance in high-resolution cam-era images.

Approaching Mars and Entering Orbit

The mission's approach phase begins two months before arrival at Mars and extends

until the spacecraft gets a health check after it begins orbiting Mars. The most criticalevent is the "Mars orbit insertion" thruster burn calculated to slow the spacecraftenough for Mars' gravity to capture it into orbit.

One month before reaching Mars, the spacecraft will begin its optical navigation experi-ment, which lasts until two days before Mars arrival. It will point the Optical NavigationCamera at Mars' moons, Phobos and Deimos. By comparing the observed positions ofthe moons to their predicted positions relative to background stars, navigators will cal-culate the precise position of the orbiter. This optical navigation is a demonstration toprepare for future missions that might use this technology. Mars ReconnaissanceOrbiter's own orbit insertion will not require use of position calculations from this exper-

iment.

Navigators' aim point for Mars Reconnaissance Orbiter is 360 kilometers (223 miles)above the planet's surface, with the spacecraft approaching from the south. The space-craft will need to slow itself by about 1,000 meters per second (about 2,200 miles perhour) in order to be captured into orbit. The six main engines will fire for about 25 min-utes. About 15 minutes into the burn, the spacecraft will pass as close to the planet'ssurface as it will get on this day, and at about that same time it will both enter into

26


29/47

Mars' shadow and slip behind Mars from Earth's perspective. Until it goes behindMars, the spacecraft will be in communication with Earth during the orbit-insertion burn.The burn will end while the spacecraft is out of communication, and the orbiter willreappear and re-establish communications after about 30 suspenseful minutes withouta signal.

If orbit insertion goes exactly as planned, the first orbit will take 35 hours to complete,as the spacecraft swings out as far as 44,500 kilometers (27,700 miles) from the planetbefore completing the circuit with an approach to about 300 kilometers (186 miles)above Mars' surface. The ground crew will assess the orbiter's health and run a finalrehearsal of aerobraking procedures before beginning aerobraking activities.

Aerobraking

Aerobraking uses friction with the planet's upper atmosphere to slow the orbitingspacecraft and change the shape of its orbit. The shape of the orbit Mars

Reconnaissance Orbiter should fly for making best use of its science instruments hasbeen carefully designed. The desired orbit is a near-polar, low-altitude orbit whosemost distant altitude at 320 kilometers (199 miles) is about 25 percent farther from theplanet than its closest point at 255 kilometers (158 miles). Initially, the orbit-insertionengine burn will put the spacecraft into an orbit with a very different shape, with themost distant point about 15,000 percent farther from the planet than the closest point.The mission will use hundreds of carefully calculated aerobraking dips into the upperatmosphere over the course of about six months to achieve that dramatic change inshape.

The process uses brief burns from the thrusters while the spacecraft is at the far end ofthe ellipse --called the "apoasis." The burns are used only to adjust how deeply thespacecraft dips into the atmosphere at the "periapsis" end of the ellipse, where theorbit comes closest to the planet. It is the atmospheric drag on the spacecraft duringthe periapsis part of the orbit that does most of the work to decrease the apoapsis alti-tude. Compared to relying only on rocket engines to shape orbits, aerobraking reducesthe amount of fuel that must be launched from Earth by nearly one-half. This is themotive for aerobraking, a technique NASA has previously used with success for theMars Global Surveyor and Mars Odyssey orbiters.

Generally, the density of a planetary atmosphere decreases with increasing altitude.

However, Mars' upper atmosphere is quite changeable in how dense it is at any givenaltitude. Experience gained from earlier orbiters plus monitoring by this mission's ownAtmospheric Structure Investigation will aid calculations of how low to bring the periap-sis from day to day. This constant monitoring is necessary because efficient aerobrak-ing requires a balance between getting enough friction to slow the spacecraft but nottoo much heating. Too much friction could overheat the spacecraft. Too little could pre-vent getting the orbit to the right shape in time to lock it into the desired time-of-daypattern for the mission's science phase.

27


30/47

In its configuration for aerobraking, the orbiter presents a frontal area of 37.5 squaremeters (404 square feet) including the back surfaces of the solar panels and high-gainantenna. The more compact and massive main structure of the spacecraft is out infront of these larger surfaces in the direction of travel. This configuration gives the

spacecraft a self-righting stability comparable to a badminton shuttlecock.

Mars Reconnaissance Orbiter will begin aerobraking about a week after arriving atMars. The process will start with a "walk-in" phase for about 12 days, then switch to amain phase of aerobraking lasting up to five-and-a-half months, concluding with a"walk-out" phase of about five days.

During walk-in, thruster burns when the spacecraft is farthest from the planet will incre-mentally lower the other end of the orbit enough for the spacecraft to begin encounter-ing atmospheric drag. Once the periapsis lowers to the altitude where the optimalamount of atmospheric drag is found, the main phase of aerobraking will begin to use

the drag to lower the apoapsis. As the orbit shrinks in size, it will also lessen in dura-tion. At the start of the main phase of aerobraking, each orbit will take more than 30hours to complete. By the end of the main phase, the spacecraft will be completing anorbit every two hours. The walk-out phase will raise the periapsis back out of theatmosphere. This will slow the final process and prevent overheating during long dragpasses as the orbit becomes more circular and the speed at periapsis is significantlyreduced.

After aerobraking has been completed, a few transition activities in September andOctober 2006 will get the orbiter ready to begin its primary science phase. Theseinclude three or four thruster-firing maneuvers for fine-tuning the shape of the orbit,

deployment of the antenna for the radar, opening the cover on the imaging spectrome-ter, and final testing and calibration of scientific instruments.

The orbit and the spacecraft will be ready for the start of the mission's main event, theprimary science phase. But just before that phase begins, the geometry of the Sun,Earth and Mars will affect communications while Mars passes behind the Sun, fromEarth's perspective. This event, called a "solar conjunction," occurs about every 26months. Radio signals between Mars and Earth during a conjunction pass too close tothe Sun to be received reliably. For mission-planning purposes, the conjunction is con-sidered to last as long as Mars and the Sun are less than five degrees apart in Earth'ssky, from Oct. 7, 2006, to Nov. 8, 2006.

Science Phase

During its primary science phase, from November 2006 to December 2008, MarsReconnaissance Orbiter will examine parts of the planet in unprecedented detail andmonitor the entire planet daily throughout a full cycle of Martian seasons. Beginningright after solar conjunction allows slightly more than one Martian year of observationswithout interruption by another conjunction. Mars will be about one-third of the way

28


31/47

through a northern hemisphere summer in November 2006.Throughout the science phase, the orbiter will generally keep its instruments pointed atMars to collect data and its high-gain antenna pointed at Earth to send the data home.With daily support by NASA's Deep Space Network for receiving the data on Earth,Mars Reconnaissance Orbiter will return more than five times as much data as all pre-

vious missions to Mars combined.

The primary science orbit is designed to serve the mission's research goals. Thespacecraft will pass almost directly over the poles on each orbit. The orbit will remainat a fixed angle to the Sun; every time the spacecraft passes northbound over theequator, it will see mid-afternoon lighting on the ground. A complete orbit will takeabout 1 hour and 52 minutes. By the next time the orbiter comes around and crossesthe equator again, the planet underneath will have rotated just enough that the orbitersees the same time-of-day on the ground beneath it.

In altitude, the slightly elliptical orbit will range from 255 kilometers (158 miles) at the

low point, or periapsis, to 320 kilometers (199 miles) at the highest point, or apoapsis.The periapsis will be over the south pole, the apoapsis over the north pole. This shapereflects the slightly asymmetrical shape of Mars and so it deviates from a circular orbit.For comparison with the orbiters currently at Mars, Mars Global Surveyor flies a nearlycircular orbit at about 378 kilometers (235 miles), Mars Odyssey flies one at 400 kilo-meters (250 miles), and Mars Express flies an elliptical, 7.5-hour orbit ranging from259 to 11,560 kilometers (161 to 7,183 miles).

The primary science orbit for Mars Reconnaissance Orbiter will have two cycles ofrepeating its ground track to allow researchers to go back for a closer look at featuresseen in regional surveys. That is, 359 days after any given orbit, the spacecraft willrepeat essentially the same path as the earlier orbit. However, there is a much shortercycle of 17 days in which any place on the planet can be viewed by rolling the space-craft up to 20 degrees to the left or right of straight-downward (nadir) pointing of theinstrument deck. Thus, a given target can be viewed in any 17-day cycle or can beviewed from different direction (e.g., as need for stereo images) in two successivecycles.

Relay Phase

A two-year phase when the top priority for Mars Reconnaissance Orbiter will be com-

munications support for other missions is scheduled to begin when the primary sciencephase ends in December 2008 and run for two years. Important relay support willbegin before that, however.

The Electra communications package on Mars Reconnaissance Orbiter will enable theorbiter to assist with navigation and communication for spacecraft arriving at Mars. Itwill be able to communicate with spacecraft on the surface of Mars at data rates from 1kilobit per second to 2 megabits per second. The relay can work only when the orbiter

29


32/47

is about 20 degrees or more above the horizon from the perspective of a lander orrover on the surface. Due to the orbiter's relatively low altitude, that will limit each relaysession to about five minutes or less. Communications between the orbiter and a lan-der or rover will take advantage of the development of an international standard, calledthe Proximity-1 protocol, for the data transfer. The Consultative Committee for Space

Data Systems, an international partnership for standardizing techniques used for han-dling space data, developed Proximity-1.

NASA's Phoenix Mars Scout mission is in development for launch in August 2007 andlanding in May 2008. Phoenix would land in icy soils near the north polar ice cap ofMars and spend up to three months examining the history of the water in these soils,checking for organic chemicals and monitoring polar climate. Plans for the Phoenixmission envision support from Mars Reconnaissance Orbiter for navigation and com-munication during the approach to Mars, then two to three relay contacts daily at ratesof up to 128 kilobits per second during Phoenix' surface operations.

The surprisingly long lives of NASA's Mars Exploration Rovers have raised the possi-bility that either Spirit or Opportunity will be the first user of Mars ReconnaissanceOrbiter's relay capabilities. Those rovers have relied on NASA's Mars Odyssey forrelaying more than 90 percent of the data they have returned, and have also usedNASA's Mars Global Surveyor and the European Space Agency's Mars Express torelay data.

NASA's Jet Propulsion Laboratory is developing the next-generation Mars rover, with ascience payload about 10 times as massive as the current rovers'. This rover, calledMars Science Laboratory, is slated for launch in October 2009 and landing on Mars inOctober 2010. Mars Reconnaissance Orbiter will have an important role as communi-

cations relay for Mars Science laboratory.

End of Mission

The Mars Reconnaissance Orbiter's prime mission will end Dec. 31, 2010, after thetwo-year-long relay phase. If left at the low-altitude orbit used during the prime mission,the spacecraft could be expected to gradually lose altitude due to friction with theupper reaches of the atmosphere, and might fall to the planet's surface within a fewyears. Instead, at the end of the prime mission, the orbiter's thrusters will take thespacecraft to a higher orbit so that it will remain in orbit for decades. The end-of-mis-sion orbit will be an ellipse ranging in altitude from about 350 to 410 kilometers (217 to

255 miles).

The initial launch mass of the orbiter will includes more than enough propellant for theprime mission. Even after the end-of-mission maneuver, the orbiter is expected to haveenough extra propellant for about five additional years of operation. Unless that propel-lant is needed for contingencies during the prime mission, NASA would have the optionof assigning the orbiter an extended mission to continue support for future Mars mis-sions. From the end-of-mission orbit, Mars Reconnaissance Orbiter could supplement

30


33/47

the relay support and would still be NASA's most capable asset for evaluating potentiallanding sites for future missions even though imaging resolution would be reduced by30 percent at the higher altitude. Assuming its atmospheric instruments were still oper-ating, the Mars Reconnaissance Orbiter could also provide near-real-time support forfuture landers, just as Mars Global Surveyor did for the Mars Exploration Rovers.

Communications

From launch day until the end of its operations, Mars Reconnaissance Orbiter will relyon NASA's Deep Space Network of antenna stations on Earth. The radio links betweenthe spacecraft and the Deep Space Network antennas will provide tracking capabilityduring the trip to Mars; uplinked commands to the spacecraft; and downlink of all theengineering, science-instrument and relayed data from the orbiter.

The Deep Space Network transmits and receives radio signals through large dishantennas at three sites spaced approximately one-third of the way around the world

from each other. This configuration ensures that spacecraft remain in view of oneantenna complex or another as Earth rotates. The antenna complexes are atGoldstone in California's Mojave Desert; near Madrid, Spain; and near Canberra,Australia. Each complex is equipped with one antenna 70 meters (230 feet) in diame-ter, at least two antennas 34 meters (112 feet) in diameter, and smaller antennas. Allthree complexes communicate directly with the control hub at NASA's Jet PropulsionLaboratory, Pasadena, Calif. The network provided routine communications for 30 fly-ing spacecraft during the second quarter of 2005.

The orbiter is expected to return 34 terabits of data during its primary science phase,more than five times all previous Mars missions combined. Most of that data will come

through two sessions per day, each about eight hours long, using 34-meter antennas.Plans call for using 70-meter antennas for supplemental coverage during the portionsof the primary science when Mars is farthest from Earth.

Mars and Earth will be about 384 million kilometers (2.39 million miles) apart -- nearlytheir maximum distance from each other -- right at the beginning of the orbiter's prima-ry science phase in November 2006. At that distance, radio signals traveling at thespeed of light take about 21 minutes to make the one-way trip, and the orbiter isexpected to send data to a 34-meter antenna on Earth at a rate of about 600 kilobitsper second (about three CD-ROMs worth of data per hour). The minimum Earth-Mars

distance during the orbiter's prime mission will be in December 2007, when the twoplanets will come within 88 million kilometers (55 million miles) of each other. Radiosignals travel that distance in about four minutes, and Mars Reconnaissance Orbiter isexpected to transmit to a 34-meter antenna that far away at a rate of about 2.6megabits per second (about 14 CD-ROMs worth of data per hour). The spacecraft'smaximum data-transmission rate, with a 70-meter antenna on the receiving end, isexpected to be about 3.5 megabits per second, fast enough to fill a CD-ROM in aboutthree minutes.

31


34/47

The mission will use X-band radio frequencies as its principal communication channelwith Earth. Counting the capacity from supplemental use of 70-meter antennas as wellas two daily sessions with 34-meter ones, the quantity of data received per day via Xband is expected to vary from about 40 to 90 gigabits (about 60 to 140 CD-ROMsworth). The mission will also demonstrate the use of Ka band radio frequencies. After

that demonstration's goals are met, Ka band transmissions might add significantly tothe total amount of science data sent to Earth by the orbiter. The Ka band equipmentuses less power than its X band counterpart to send the same amount of data.However, Ka band transmissions are more susceptible to being disrupted by water inEarth's atmosphere

Planetary Protection Requirements

In the study of whether Mars has had environments conducive to life, precautions aretaken against introducing microbes from Earth. The United States is a signatory to aninternational treaty that stipulates that exploration must be conducted in a manner that

avoids harmful contamination of celestial bodies. In compliance with that treaty, theflight hardware of the Mars Reconnaissance Orbiter has been designed to meetNASA's Planetary Protection Policy.

For a planetary orbiter mission such as this, the current policy offers two alternativestrategies: by assuring a long-term orbital lifetime (more than 50 years) or by flying avery clean spacecraft (measured by a microbiological burden of no more than 50,000microbial spores). The low-altitude orbit needed for the mission to achieve its sciencegoals makes it unfeasible to depend on impact avoidance, since a low-altitude space-craft failure could result in an impact of Mars considerably before 50 years passes.

Consequently, the project has demonstrated compliance with the total microbiologicalburden requirement.

In the event of a premature entry into the martian atmosphere, portions of the space-craft that will be heated to 500 degrees Celsius (932 degrees Fahrenheit) or hotter forat least half a second during friction with Mars' atmosphere will be sterilized by thatprocess. For other parts of the spacecraft, a combination of dry-heat microbial reduc-tion, manufacturing controls and cleaning are keeping the number of spores within per-missible levels.

Another type of precaution is to be sure any hardware that doesn't meet these stan-

dards does not go to Mars accidentally. When the Atlas V's Centaur upper stage sepa-rates from the spacecraft, the two objects are traveling on nearly identical trajectories.To prevent the possibility of the Centaur hitting Mars, that shared course is deliberatelyset so that the spacecraft would miss Mars if not for its first trajectory correctionmaneuver, about 15 days later.

The NASA planetary protection officer is responsible for the establishment andenforcement of the agency's planetary protection regulations.

32


35/47

Spacecraft

The Mars Reconnaissance Orbiter spacecraft consists of the payload and the systems

that enable the payload to do its job and send home the results.

The spacecraft has been assembled around a main structure made of strong, light-

weight materials including titanium, carbon composites and aluminum honeycomb.

Propulsion Subsystem

The spacecraft's propulsion system will perform maneuvers such as trajectory correc-

tions during the cruise to Mars, braking to insert the spacecraft into orbit the day it

arrives, and orbit adjustments during aerobraking.

The orbiter carries a total of 20 small rocket engines, or thrusters, of three sizes. Thesix largest ones each produce about 170 newtons (38 pounds) of thrust when they are

in use. The main function for these six is to slow the spacecraft's velocity as it first flies

close to Mars so that it will be captured into orbit by Mars' gravity. All six will fire at the

same time for this mission-critical event, called Mars orbit insertion. By using relatively

small engines rather than a single larger one, the mission is less susceptible to an

orbit-insertion failure due to an engine malfunction. The six 170-newton thrusters will

also be used for the spacecraft's first trajectory correction maneuver, scheduled for 15

days after launch.

Six intermediate thrusters can each produce 22 newtons (5 pounds) of thrust. They willbe used for other trajectory correction maneuvers during the trip to Mars and for the

maneuvers to adjust the altitude of aerobraking dips into the upper atmosphere. The

smallest eight thrusters each produce 0.9 newtons (0.2 pounds) of thrust. They can

control the orientation of the spacecraft as an alternate system to attitude-control reac-

tion wheels or when the momentum built up in the wheels needs to be reduced. They

will also be used to control ro

NASA 124378main mro-launch-Aug051

Documents

Transcript of NASA 124378main mro-launch-Aug051